1. The Field Of the Invention
The present invention relates to an airborne multi-spectral sensor system that utilizes real-time acquisition of images in many narrow, contiguous spectral bands, to generate hyper-spectral image data, and in particular to image data sets which can be used individually or combined to get spectral profiles and emittance to identify ground targets.
2. The Prior Art
There are many known apparatus for making airborne surveys of terrain for many purposes. These apparatus generally have a plurality of optical scanning devices which are directed toward the ground and form images which are translated into electronic signals for rapid comparison by computers. For example U.S. Pat. No. 4,057,734 shows radiometric calibration (which is standard for scanners) as wavelength calibration to compensate for variation in the intensity of the incoming radiation due to random fluctuations. U.S. Pat. No. 4,616,134 relates to a laboratory instrument. In order to obtain the apparent thermal inertia, it is necessary to measure the difference between maximum and minimum temperature occurring during a diurnal solar cycle. At C down 1, lines 55-61 discuss differential thermal reflectance (it should be "differential thermal radiance") by heating of the sample. U.S. Pat. No. 4,908,705 shows a steerable wide-angle imaging system which is particularly effective for high speed, low altitude reconnaissance. U.S. Pat. No. 4,939,369 discloses an imaging and tracking system which utilizes multiple arrays of sensors. U.S. Pat. No. 5,028,998 concerns a system which provides an electronic zoom feature to effectively produce a constant altitude picture as the terrain varies while the airborne platform remains at a constant average altitude. U.S. Pat. No. 5,047,783 provides for improved imaging from radiation detectors by noise cancellation. U.S. Pat. No. 5,116,118 describes another airborne imaging system. U.S. Pat. No. 5,149,959 does not have substantially continuous in-flight calibration of the system to compensate for any changes which may take place between the time the system is preflight calibrated on the ground and when it is airborne and begins gathering data. It also lacks means to monitor the flight characteristics of the system through a comparison of the aircraft performance and platform performance.